Calibration of camera devices often involves taking of images of one or more calibration targets at different distances from a camera device. The capture of multiple targets at different distances can be particularly important in the case of a camera device which includes multiple camera modules that capture different images from which depth or other image information may be obtained.
In order to capture depth information and/or support computational photography where multiple images may be combined to generate an output image, camera devices may, and sometimes do, include more than one camera module. In order to facilitate combining of images captured by different camera modules of a camera device, it often useful to know the spatial relationship of the cameras and the field of view which will be captured by each camera for one or more camera settings.
While a camera may be manufactured with the intent of a particular spatial relationship between the camera's modules, due to mounting issues, manufacturing tolerances and/or other reasons, the precise physical relationship between the camera's modules may not be known to the extent desired simply from the design specifications.
In the case where a camera includes numerous camera modules the complexity in achieving precise camera alignment between the many camera modules of a camera increases as the number of camera modules increases. For example, achieving a precise alignment between 6 camera modules is far more complicated from a manufacturing perspective than achieving alignment between two camera modules.
Given that there may be minor differences in the spatial relationship from one camera device to another camera device, particularly in the case where a camera device includes a large number of camera modules, calibration of the camera device can be important.
Camera device calibration may require the taking of images of one or more test patterns, e.g., with the test patterns being at different distances from the camera device to be calibrated. While it might be possible to take a camera device from one test rig to another test rig with the calibration targets being at different distances from the camera device in each test rig, such an approach to capturing the images for calibrating a camera can be time consuming. In addition, having multiple test rigs with targets at different distances can involve the use of a fair amount of floor space. Dedicating a large amount of floor space to calibration rigs can be costly, given that manufacturing and/or space is often rented on a square foot basis.
In view of the above discussion it should be appreciated that there is a need for improved calibration apparatus which would allow images of targets at different distances from a camera to be captured in a single apparatus, preferably without the need to move the camera device being calibrated between captures of images of calibration targets. While not essential, it would be desirable from a cost and manufacturing materials perspective if the calibration apparatus could be implemented in a relatively small form without requiring a large amount of floor space to store or use.